Most doctors if they needed to could kind their own letters and memos on a typewriter or word processor and deliver them to the post office. Yet most doctors as well as other professions hire a typist to do these tasks. Using theories of international trade describe why a doctor would hire a typist to type his letters and memos even if he could do it himself. If a particular doctor possibly will type faster than the fastest typist explain why he still might hire a typist to type his letters and memos. Use what you have erudite from international trade theory in answering this question